Bead breakers for separating a tire bead from a tire rim are well known. With respect to heavy equipment tires, a tire change is more often than not accomplished in a field or remote location from repair facilities because of the difficulty of transporting heavy equipment. For this reason, portable tire bead breakers ar in demand. Such portable tire bead breakers require portability and ease of use as well as reliability in breaking free a tire bead from a tire rim. As can be expected, a tire bead which is normally inflated with air pressure to seal with respect to a tire rim becomes very tightly engaged with a tire rim in heavy equipment over a period of time and use.
One of the problems with tire bead breakers is the inability to control the bead breaker with respect to the flexibility of the tire. For example, in U.S. Pat. No. 4,589,462, a bead breaker tool has a roller member which engages a tire rim and a jaw member which is inserted between a lip of a tire rim and a tire. The jaw member and roller member are pivotally coupled to one another and actuated by a manually operated screw member. The jaw member is slidably mounted in a frame member so that another screw member can move the jaw member laterally relative to a frame member. The problem with this device is that it often fails because the friction between the slidable jaw member and frame member is too great to overcome and because the jaw member often tends to exert a movement or force on the tire wall which is upward relative to a tire rim rather than inward so that the tire wall can be damaged before the type bead breaks.
Another device called a "Bead Buster" and sold by Gans Tire Co., Inc., 730 Eastern Ave., P.O. Box 22, Malden, Mass. 02148 involves a set of side-by-side wedge elements which are forced into place between a tire and a tire rim by hammer blows on a strike plate. Once positioned, a cam locking device is adjusted by an adjuster screw to orient the device at a position 90.degree. to the rim. A cam device then locks the tool to the rim. A ratchet wrench operates a threaded member to move a set of wedge elements perpendicular to the tool. The tool suffers from friction when the threaded member is actuated which can only be alleviated by expensive load bearing ball bearings or the like. Additionally the tire, during the bead breaking operation, sometimes moves erratically which causes the tool to be forced off the rim or to puncture or damage the tire wall.